﻿using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Caching;
using SqlSugar;

namespace WebSite.Class
{
    public class HttpRuntimeCache : ICacheService
    {
        public void Add<TV>(string key, TV value)
        {
            HttpRuntimeCacheHelper<TV>.GetInstance().Add(key, value);
        }

        public void Add<TV>(string key, TV value, int cacheDurationInSeconds)
        {
            HttpRuntimeCacheHelper<TV>.GetInstance().Add(key, value, cacheDurationInSeconds);
        }

        public bool ContainsKey<TV>(string key)
        {
            return HttpRuntimeCacheHelper<TV>.GetInstance().ContainsKey(key);
        }

        public TV Get<TV>(string key)
        {
            return HttpRuntimeCacheHelper<TV>.GetInstance().Get(key);
        }

        public IEnumerable<string> GetAllKey<TV>()
        {
            return HttpRuntimeCacheHelper<TV>.GetInstance().GetAllKey();
        }

        public TV GetOrCreate<TV>(string cacheKey, Func<TV> create, int cacheDurationInSeconds = int.MaxValue)
        {
            var cacheManager = HttpRuntimeCacheHelper<TV>.GetInstance();
            if (cacheManager.ContainsKey(cacheKey))
            {
                return cacheManager[cacheKey];
            }
            else
            {
                var result = create();
                cacheManager.Add(cacheKey, result, cacheDurationInSeconds);
                return result;
            }
        }

        public void Remove<TV>(string key)
        {
            HttpRuntimeCacheHelper<TV>.GetInstance().Remove(key);
        }
    }

    internal class HttpRuntimeCacheHelper<V>
    {
        #region 全局变量

        private static HttpRuntimeCacheHelper<V> _instance = null;
        private static readonly object InstanceLock = new object();

        #endregion

        #region 构造函数

        private HttpRuntimeCacheHelper()
        {
        }

        #endregion

        #region 属性

        /// <summary>         
        ///根据key获取value     
        /// </summary>         
        /// <value></value>      
        public V this[string key] => (V)HttpRuntime.Cache[CreateKey(key)];

        #endregion

        #region 公共函数

        /// <summary>         
        /// key是否存在       
        /// </summary>         
        /// <param name="key">key</param>         
        /// <returns> ///  存在<c>true</c> 不存在<c>false</c>.        /// /// </returns>         
        public bool ContainsKey(string key)
        {
            return HttpRuntime.Cache[CreateKey(key)] != null;
        }

        /// <summary>         
        /// 获取缓存值         
        /// </summary>         
        /// <param name="key">key</param>         
        /// <returns></returns>         
        public V Get(string key)
        {
            return (V)HttpRuntime.Cache.Get(CreateKey(key));
        }

        /// <summary>         
        /// 获取实例 （单例模式）       
        /// </summary>         
        /// <returns></returns>         
        public static HttpRuntimeCacheHelper<V> GetInstance()
        {
            if (_instance != null) return _instance;
            lock (InstanceLock)
                if (_instance == null)
                    _instance = new HttpRuntimeCacheHelper<V>();
            return _instance;
        }

        /// <summary>         
        /// 插入缓存(默认20分钟)        
        /// </summary>         
        /// <param name="key"> key</param>         
        /// <param name="value">value</param>          
        public void Add(string key, V value)
        {
            Add(key, value, 60 * 20);
        }

        /// <summary>         
        /// 插入缓存        
        /// </summary>         
        /// <param name="key"> key</param>         
        /// <param name="value">value</param>         
        /// <param name="cacheDurationInSeconds">过期时间单位秒</param>         
        public void Add(string key, V value, int cacheDurationInSeconds)
        {
            Add(key, value, cacheDurationInSeconds, CacheItemPriority.Default);
        }

        /// <summary>         
        /// 插入缓存.         
        /// </summary>         
        /// <param name="key">key</param>         
        /// <param name="value">value</param>         
        /// <param name="cacheDurationInSeconds">过期时间单位秒</param>         
        /// <param name="priority">缓存项属性</param>         
        public void Add(string key, V value, int cacheDurationInSeconds, CacheItemPriority priority)
        {
            string keyString = CreateKey(key);
            HttpRuntime.Cache.Insert(keyString, value, null, DateTime.Now.AddSeconds(cacheDurationInSeconds), Cache.NoSlidingExpiration, priority, null);
        }

        /// <summary>         
        /// 插入缓存.         
        /// </summary>         
        /// <param name="key">key</param>         
        /// <param name="value">value</param>         
        /// <param name="cacheDurationInSeconds">过期时间单位秒</param>
        /// <param name="dependency"></param>
        /// <param name="priority">缓存项属性</param>         
        public void Add(string key, V value, int cacheDurationInSeconds, CacheDependency dependency,
            CacheItemPriority priority)
        {
            string keyString = CreateKey(key);
            HttpRuntime.Cache.Insert(keyString, value, dependency, DateTime.Now.AddSeconds(cacheDurationInSeconds), Cache.NoSlidingExpiration, priority, null);
        }

        /// <summary>         
        /// 删除缓存         
        /// </summary>         
        /// <param name="key">key</param>         
        public void Remove(string key)
        {
            HttpRuntime.Cache.Remove(CreateKey(key));
        }

        /// <summary>
        /// 清除所有缓存
        /// </summary>
        public void RemoveAll()
        {
            var cache = HttpRuntime.Cache;
            IDictionaryEnumerator cacheEnum = cache.GetEnumerator();
            ArrayList al = new ArrayList();
            while (cacheEnum.MoveNext())
            {
                al.Add(cacheEnum.Key);
            }

            foreach (string key in al)
            {
                cache.Remove(key);
            }
        }

        /// <summary>
        /// 清除所有包含关键字的缓存
        /// </summary>
        /// <param name="removeExpression"></param>
        public void RemoveAll(Func<string, bool> removeExpression)
        {
            var allKeyList = GetAllKey();
            var delKeyList = allKeyList.Where(removeExpression).ToList();
            foreach (var key in delKeyList)
            {
                HttpRuntime.Cache.Remove(key);
            }
        }

        /// <summary>
        /// 获取所有缓存key
        /// </summary>
        /// <returns></returns>
        public IEnumerable<string> GetAllKey()
        {
            IDictionaryEnumerator cacheEnum = HttpRuntime.Cache.GetEnumerator();
            while (cacheEnum.MoveNext())
            {
                if (cacheEnum.Key != null) yield return cacheEnum.Key.ToString();
            }
        }

        #endregion

        #region 私有函数

        /// <summary>         
        ///创建KEY   
        /// </summary>         
        /// <param name="key">Key</param>         
        /// <returns></returns>         
        private string CreateKey(string key)
        {
            return key;
        }

        #endregion
    }
}